1. Field of the Invention
The present disclosure is generally related to aerial refueling booms used in aerial refueling systems and more particularly, to articulated boom nozzles attached to the aerial refueling booms.
2. Related Art
Aerial refueling aircraft utilize aerial refueling booms to transfer fuel from tanks within the aerial refueling aircraft to an aircraft receiving the fuel while in flight. Turning to FIG. 1, an example of an implementation of a known approach to refuel a receiving aircraft 100 with an aerial refueling aircraft 102 utilizing an aerial refueling boom 104 is shown. In this example, the aerial refueling boom 104 is pivotally mounted at one end 106 of the aerial refueling aircraft 102. The aerial refueling boom 104 typically includes an articulated boom nozzle 108 at the opposite end of the aerial refueling boom 104. The articulated boom nozzle 108 connects to a corresponding fuel receptacle on the receiving aircraft 100. The aerial refueling boom 104 may be pivotally mounted to the aerial refueling aircraft 102 via a gimbal-type structure 116 and the aerial refueling boom 104 may be lowered from and raised to the tail 114 of the aerial refueling aircraft 102 via a combination of control surfaces 110 (that typically include elevator and rudder surfaces) and a hoist-cable 112. The aerial refueling boom 104 may comprise two aerodynamically faired tubes with one telescoping within the other, and a sliding seal to provide passage of fuel without leakage. Once the articulated boom nozzle 108 is connected to the fuel receptacle of the receiving aircraft 100, fuel is transferred from the tanks within the aerial refueling aircraft 102 to the receiving aircraft 100 via the aerial refueling boom 104.
The articulated boom nozzle 108 may incorporate a ball joint swivel and a universal joint, both of which provide flexibility to the articulated boom nozzle that is required when making contact with the fuel receptacle of the receiving aircraft 100 and when the aerial refueling aircraft 102 and the receiving aircraft 100 are hooked up. The universal joint is used to transmit impact loads through the articulated boom nozzle to a shock absorber recoil assembly, and the ball joint swivel may allow movement about two independent axes, one in a 60°, for example, conical motion, and the other in a ±30° or ±45°, for example, up and down (elevation) or side to side (azimuth) motion. When the insertion is completed, an automatic load alleviation system (ALAS) may be automatically activated, which provides automatic disconnects of the articulated boom nozzle 108 if preselected limits are exceeded.
Generally, an articulated boom nozzle may be approximately two feet long and may comprise an independent disconnect system (IDS). In one type of an IDS, electrical power is supplied from the aerial refueling aircraft 102 through wiring in the aerial refueling boom 104 that is connected to an electrical connector on the articulated boom nozzle 108, and the IDS may be operated by a boom operator in the aerial refueling aircraft 102 depressing a disconnect switch through the second detent. When the IDS is activated by the boom operator depressing the disconnect switch, an electrical signal is sent to a solenoid that retracts IDS toggle latches on each side of the articulated boom nozzle 108 to a flush position, which allows the aerial refueling boom 104 to be retracted from the receiver aircraft while its receptacles toggles are in the latched/extended position. The IDS toggle latches may have a holding circuit installed that retains them in the retracted position after IDS actuation, until a RESET TO READY button is pushed.
Turning to FIG. 2, a known articulated boom nozzle 200 attached to the aft end of an aerial refueling boom 202 is shown. In FIG. 2, the articulated boom nozzle 200 is attached to the aft end of an aerial refueling boom 202 through a fuel-tight flange 204. Ball 210 is part of a ball and joint swivel that is covered by outlet housing 212, where the ball and joint swivel provides flexibility to the articulated boom nozzle 200 by allowing movement in a conical symmetry about the aerial refueling boom axis. The articulated boom nozzle 200 may include 2 IDS toggle latches, one of which is shown in FIG. 2 as IDS toggle latch 220. The IDS may be an electrically controlled, pneumatically actuated system located in the articulated boom nozzle 200, whereby pneumatic pressure is supplied to the articulated boom nozzle 200 from a compressed air reservoir mounted on the aerial refueling boom 202 through cable 214. In other implementations, electrical power may be supplied from the aerial refueling boom by electrical wiring connected to electrical connectors on the articulated boom nozzle, whereby an electrical signal is sent to a solenoid that retracts the IDS toggle latches or other electrical signals are sent to an induction coil that allows the aerial refueling aircraft and the receiving aircraft to share interphone communications.
FIG. 3 is a section top plan view of a known articulated boom nozzle 300, with the nozzle tip 302 rotated left 30°. Positioned at the forward side of the articulated boom nozzle 300 is closeout ring 304. Wiring (which may be in the form of a shielded twisted-pair cable) for an IDS, a Voice Coil or an induction coil for interphone communications between an aerial refueling aircraft 102 and a receiving aircraft 100, and other signal communications may be connected to the articulated boom nozzle 300 through an electrical connector (not shown) at a 12 o'clock position on the closeout ring 304.
Within the closeout ring 304, the wiring is shown in FIG. 3 as internal wiring 310, which in the case of the wiring for the IDS, passes through a retaining ring 312 to a service loop 314 at the forward end of the articulated boom nozzle 300. The IDS wiring is connected to a solenoid 324, which, when energized by a boom operator in the aerial refueling aircraft, causes an armature 326 to shift along a longitudinal axis of the articulated boom nozzle 300, thus retracting toggle latches 328a and 328b located at the 3 o'clock and 9 o'clock positions, respectively, on the articulated boom nozzle 300. As the articulated boom nozzle 300 deflects, the internal wiring 310 is pulled from service loop 314, and as the articulated boom nozzle 300 returns to its neutral position, the internal wiring 310 is pushed back up the central bore 318 of shaft 320 and into the service loop 314.
As the articulated boom nozzle 300 is deflected, it swivels around the ball 340, causing bearing plate 342 to impinge upon ball saddle 344, thereby compressing ball joint centering spring 346. When the articulated boom nozzle 300 is signaled to return to its neutral position, the tension in the ball joint centering spring 346 assists the return.
The articulated boom nozzle 300 of FIG. 3 allows the operation of boom nozzle toggle latches by a boom operator without depending upon operation of receptacle latches on the receiving aircraft. However, there is a potential wear issue with the internal wiring at the articulating joint and the service loop as the articulated boom nozzle 300 of FIG. 3 is deflected and then returned to its neutral position. Therefore, there is a need for an articulated boom nozzle with an improved internal electrical wiring system that remains stationary while the articulated boom nozzle deflects, and a cable assembly connecting the aft end of an aerial refueling boom to a connector on the articulated boom nozzle, where a torsion cable reel assembly maintains tension on the cable assembly during movement of the articulated boom nozzle.